The present invention generally relates to mechanized harvesting and mowing equipment used on tractors or combines and, more particularly, pertains to improvements to power sickles that employ an endless cutter type mechanism.
Endless cutters offer substantial advantages over conventional reciprocating designs. In general terms, such cutters utilize a closed loop of traveling cutting blades in concert with a series of fixed cutting blades. The closed loop is continually transported in one direction only and at constant speed past the fixed blades such that each of the traveling blades repeatedly engages each of the stationary blades in a sequential fashion to provide a continuous cutting action. The smooth operation of this type of mechanism alleviates the tremendous vibrational forces inherent in reciprocating systems which can be destructive to not only the components of the cutter mechanism itself, but to any machinery which may be subject to the vibration. Additionally, an endless mower configuration is free from the noise that results directly from the reciprocation of components in a conventional system which typically presents a considerable nuisance that can substantially wear down and impair an operator who may be subjected to such noise for an extended period of time. Finally, endless mower systems do not suffer from the power losses inherent in a reciprocating system which must repeatedly accelerate and decelerate the substantial mass associated with the reciprocating componentry.
While the various endless cutting mechanisms that have, to date, been devised do overcome the disadvantages inherent in reciprocating systems they, nonetheless, suffer from a number of shortcomings. A feature lacking in the presently known endless cutter systems is any capability for enabling the size of the cutter to be relatively easily tailored to variously sized equipment. It would be most desirable for substantially the same apparatus to be adaptable to a small tractor, as well as to a large combine without the need for redesign and by employing substantially the same components.
In endless cutter systems employing a drive chain to transport the traveling blades past the fixed blades, it is essential that the position of each traveling blade is sufficiently controlled so that a proper cutting action results upon engaging each fixed blade. However, it is also important to minimize friction encountered by the chain in order to reduce wear and tear and minimize power losses. A satisfactory solution addressing both of these problems has not been incorporated in heretofore known endless cutter systems. A further source of friction and the consequential inefficiencies resulting therefrom is the speed at which heretofore used blade configurations are required to engage one another in order to achieve a proper cutting action. The geometry of previously used blades have employed a negative attack angle wherein the proximal ends of the cutting surfaces of each pair of blades engage prior to their distal ends. This has the tendency to push the material to be cut out from between the blades thereby requiring either increased blade speed or vehicle speed to overcome.
A further disadvantage of previously disclosed endless cutter systems is the necessity to substantially tear down the mechanism in order to effect simple repairs, such as the replacement of high wear items. For example, replacement of a blade in systems in which the traveling blade comprises an integral component of the drive chain requires that the tension in the chain first be relieved, that the chain be disassembled and possibly completely removed from the cutter to facilitate detachment of the faulty blade, followed by the installation of a new blade, and reassembly and retensioning of the chain. Such a labor intensive procedure, aggravated by the possibility that such repair may have to be performed in a shop rather than in the field, results in extended downtime which is most undesirable, especially during the time pressures in the harvest season. An endless cutter type sickle mechanism is therefore needed that overcomes the above set forth disadvantages of presently known systems.